Unplanar non-axisymmetric inserts

Abstract

Cutting elements for incorporation in a drill bit are provided having a body having an end face interfacing with an ultra hard material cutting layer. A main depression having a nonplanar surface is formed on the substrate and extending to the peripheral edge of the substrate subjected to the highest impact loads during drilling. This edge is immediately below the edge of the cutting layer which makes direct contact with the earth formations during drilling. The main depression is formed by forming a plurality of secondary depressions or steps. A second main depression is formed by forming a plurality of secondary depressions or steps. The second main depression also extends to the peripheral edge of the substrate. An ultra hard material layer is bonded to the end face of the cutting element body over the main depressions.

What is claimed is:  
     
       1. A cutting element comprising: 
       a cylindrical body comprising an end face having a periphery;  
       a first set of abutting secondary depressions formed on the end face defining a first main depression, wherein the first main depression spans less than half of the end face and extends to the periphery;  
       a first set of ridges formed at the intersection between the first set of abutting secondary depressions wherein at least portions of the ridges of the first set are depressed relative to the end face;  
       a second set of abutting secondary depressions formed on the end face defining a second main depression, wherein the second main depression spans less than half of the end face and extends to the periphery;  
       a second set of ridges formed at the intersection between the second set of abutting secondary depressions wherein at least portions of the ridges of the second set are depressed relative to the end face;  
       an ultra hard material layer formed over the end face, wherein the thickness of the ultra hard material layer is greatest at the periphery of the end face above the first main depression.  
     
     
       2. A cutting element as recited in  claim 1  wherein the end face is convexly curved. 
     
     
       3. A cutting element as recited in  claim 1  wherein the first main depression is spaced apart from the second main depression. 
     
     
       4. A cutting element as recited in  claim 1  wherein the first main depression comprises a central longitudinal axis, wherein the second main depression comprises a central longitudinal axis, wherein the central longitudinal axis of the second main depression is offset from the central longitudinal axis of the first main depression by an angle of 180° . 
     
     
       5. A cutting element as recited in  claim 1  wherein the first main depression comprises a central longitudinal axis, wherein the second main depression comprises a central longitudinal axis, wherein the central longitudinal axis of the second main depression is offset from the central longitudinal axis of the first main depression by an angle less than 180°. 
     
     
       6. A cutting element as recited in  claim 5  wherein the central longitudinal axis of the second main depression is offset from the central longitudinal axis of the first main depression by an angle not greater than 170°. 
     
     
       7. A cutting element as recited in  claim 1  wherein the first set of abutting depressions are arranged to define a first pattern within the first main depression, wherein the second set of abutting depressions are arranged to define a second pattern within the second main depression, wherein the first pattern is different from the second pattern. 
     
     
       8. A cutting element as recited in  claim 1  wherein the first set of abutting depressions are arranged to define a first pattern within the first main depression, wherein the second set of abutting depressions are arranged to define a second pattern within the second main depression, wherein the first pattern is the same as the second pattern. 
     
     
       9. A cutting element as recited in  claim 1  further comprising: 
       a third set of abutting secondary depressions formed on the end face defining a third main depression, wherein the third main depression extends to the periphery; and  
       a third set of ridges formed at the intersection between the third set of abutting secondary depressions wherein at least portions of the ridges of the third set are depressed relative to the end face.  
     
     
       10. A cutting element as recited in  claim 9  wherein the first main depression comprises a central longitudinal axis, wherein the second main depression comprises a central longitudinal axis, wherein the third main depression comprises a central longitudinal axis and wherein the three axes are offset at an angle of 120° from each other. 
     
     
       11. A cutting element as recited in  claim 9  further comprising: 
       a fourth set of abutting secondary depressions formed on the end face defining a fourth main depression, wherein the fourth main depression extends to the periphery; and  
       a fourth set of ridges formed at the intersection between the fourth set of abutting secondary depressions wherein at least portions of the ridges of the fourth set are depressed relative to the end face.  
     
     
       12. A cutting element as recited in  claim 11  wherein the first main depression comprises a central longitudinal axis, wherein the second main depression comprises a central longitudinal axis, wherein the third main depression comprises a central longitudinal axis, wherein the fourth main depression comprises a central longitudinal axis, and wherein the four central longitudinal axes are offset at an angle of 90° from each other. 
     
     
       13. A cutting element as recited in  claim 1  wherein the first main depression comprises a periphery, wherein the second main depression comprises a periphery, and wherein a portion of each of the first and second main depression peripheries are scalloped. 
     
     
       14. A cutting element as recited in  claim 1  wherein the ridges of the first and second set comprise rounded apexes. 
     
     
       15. A cutting element as recited in  claim 1  wherein at least some of the first set abutting secondary depressions intersect a first diameter of the end face, wherein one of said at least some first set abutting secondary depressions extends to the body periphery, wherein at least some of the second set abutting secondary depressions intersect a second diameter of the end face, wherein one of said at least some of second set abutting secondary depressions extends to the body periphery. 
     
     
       16. A cutting element as recited in  claim 15  wherein the first set ridges comprise apexes intersecting the first diameter, wherein the second set of ridges comprise apexes intersecting the second diameter, each of the first set ridge apexes intersecting the first diameter at a different height level as measured from a plane perpendicularly intersecting a central axis of the body, wherein said first set ridge apex height levels decrease radially outward toward the body periphery, and wherein each of the second set ridge apexes intersecting the second diameter at a different height level as measured from a plane perpendicularly intersecting the central axis of the body, wherein said second set ridge apex height levels decrease radially outward toward the body periphery. 
     
     
       17. A cutting element as recited in  claim 15  wherein each of the first set secondary depressions extends to a minimum height level as measured from a plane perpendicularly intersecting a central axis of the body, wherein each of the first set secondary depressions minimum height level decreases arcuately away from said first diameter, and wherein each of the second set secondary depressions extends to a minimum height level as measured from a plane perpendicularly intersecting the central axis of the body, wherein each of the second set secondary depressions minimum height level decreases arcuately away from said second diameter. 
     
     
       18. A cutting element as recited in  claim 15  wherein the first main depression is symmetric about the first diameter and wherein the second main depression is symmetric about the second diameter. 
     
     
       19. A cutting element as recited in  claim 15  wherein the first diameter is the same as the second diameter. 
     
     
       20. A cutting element as recited in  claim 15  wherein the first diameter is different from the second diameter.